INTRODUCTION TO COMPONENT DESIGN IN JAVA EE
COMPONENT VS. OBJECT, JAVA EE JAVA EE DEMO
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 1 JAVA ZOOLOGY
Java Standard Edition – Java SE • Basic types, objects, classes, networking, security, • Database access, XML parsing, user interfaces Java Enterprise Edition – Java EE • Large scale, multi-tier, scalable, reliable apps, components Java Micro Edition – Java ME • Mobile devices Java FX • Rich Internet Apps, high performance, modern look and feel, • Clients for Java EE
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 2 OBJECT VS. COMPONENT
Object-based design – construct app from objects
Component-based design – construct app from preexisting service-providing components
Properties: • Encapsulation • Specification – interface • Improved reuse and evolution • Abstraction
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 3 Person joe1 = getJoe(); VALUE OBJECT VS Person joe2= getJoe(); joe1 == joe2 REFERENCE OBJECT Person bob = getBob(); Object-based design - objects have identity bob.born.equals(joe1.born) • Reference object – e.q. a Customer • One object identifies a customer in the real world • Any reference to the customer is a pointer to the Customer objects! • Changes to the customer object available to all users! • Compare identity
• Value Object - a small object that represents a simple entity like Date, Money • Multiple value objects represent the same real world thing • Hundred of objects that represent Jun 5th, 2015 • Comparing dates does not compare identify but the value! • Its equality is not based on identity: • two value objects are equal when they have the same value, • not necessarily being the same object.
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 4 OBJECT VS. COMPONENT
Component not language specific • Organization unit, building block, functional element. • Comparison • An object is a component • Collection of objects is a component
Components connect together, and usually have dependencies, although we think of a component as an independent functional block. • e.g. OSGi standard – automobiles and industry automation Component has usually specification and realization (Interfaces and implementation in the Object-based design)
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 5 OBJECT VS. COMPONENT
Object-based design – identity oriented – domain abstraction Component-based design – service oriented – functional abstraction
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 6 ENTERPRISE APP DESIGN JAVA EE
Enterprise Application (EA) • Tiered Applications • Functionality separated into isolated functional areas – tiers • e.g. • Client tier – client app • Web tier – server-side controllers • Business tier – business functions • EIS tier – data store • ..
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 7 CLIENT TIER
Usually a different machine access to Java EE server. Request – response communication Client can be • A web browser • Standalone app • Another server
Can use a different platform
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 8 WEB TIER Components handling interaction between clients and business tier. Does the following tasks • Dynamic content derivation in various formats • HTML, XML, JSON • Collect user input, return results • Control flow • Maintain state of user session • Basic logic • Java EE Technologies (later in more detail..) • Servlets, Java ServerFaces (JSF), Facelets, • Expression language, Java Server Pages (JSP), • JSP Tag library, JavaBeans Components
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 9 WEB TIER
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 10 WEB TIER – JAVA EE TECHNOLOGIES
• Servlets - classes to dynamically process request and give response in HTML • Java ServerFaces (JSF) – user interface component framework for web apps to include UI components on a page, convert, validate data, maintain state, save data • Facelets – templating ang XHTML, • Expression Language – reference Java EE components from JSP/Facelets • Java Server Pages (JSP) – Text based document compiled to servlet, define dynamic content added to static pages – e.g. HTML • JSP Tag Library – core functionality of tags • JavaBeans Components – object that acts as temporary data store for app
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 11 BUSINESS TIER
Components that provide business logic of an application. Business logic – is a code that provides functionality to a particular business domain. • Financial industry • E-commerce site
Good design has the core functionality in business tier components Java EE Technologies (later in more detail..) • Enterprise JavaBeans (EJB), JAX-RS RESTful web service endpoints, JAX-WS web service endpoints, Java Persistence API entities, Java EE manager beans.
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 12 BUSINESS TIER
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 13 BUSINESS TIER JAVA EE TECHNOLOGIES
• Enterprise JavaBeans (EJB) – component that encapsulate the core functionality of an app • JAX-RS RESTful web service endpoints – API to create web services on top of HTTP, REST – representational state transfer • JAX-WS web service endpoints – creating and consuming SOAP web services • Java Persistence API entities – API for accessing data in underlying data stores and mapping to Java objects • Java EE managed beans – managed components that may provide business logic, but do not require transaction of security features of EJB • Light weight POJO with minimal requirements • Small set of basic services
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 14 ENTERPRISE INFORMATION SYSTEM (EIS) TIER Usually contains, database servers, resource planning, legacy data sources, etc. Resources usually distributed across different machines than the Java EE server and are accessed through components in business tier. Java EE Technologies Java Database Connection API (JDBC) – low level API to access and retrieve data from data store. Connects to SQL relational database Java Persistence API (JPA) – Access the underplaying data stores through java Objects. On top of JDBC. Java EE Connector Architecture (JCA) – API to connect to enterprise resources, like resource planning, customer management system, etc. Java Transition API (JTA) – API to define and manage transitions, including distributes transactions across multiple data resources.
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 15 JAVA EE PLATFORM
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 16 JAVA EE APPLICATION SERVERS
Who understands the Java EE components?
The interpret!
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 17 JAVA EE APPLICATION SERVERS
Implements the Java EE platform API Provides standard services Hosts several application components Provides containers • Interface between component and low-level functionality • Web container (large at server) • Application client container (small at client) • EJB container (middle at server)
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 18 JAVA EE APPLICATION SERVERS Web container (1) • Interface web component and web server • Component Servlet/JSF/JSP page • Container manages its lifecycle, dispatch request, provides context information Application client container (2) • Java EE app clients using Java EE server components • Distinct machines EJB container (3) • Interface between EJB that provides business logic and the Java EE server • EJB container manages the execution of the EJB
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 19 JAVA EE APPLICATION SERVERS Web container (1)
EJB cont. (3)
Application client container (2)
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 20 JAVA EE APPLICATION SERVERS
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 21 JAVA EE API CONTAINERS
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 22 JAVA EE COMPONENTS
Functional components • Enterprise beans = Enterprise JavaBeans (EJB) • Session beans – transient conversation with client. Once client servers the session bean and its data are gone • Message driven beans – session bean features and message listener – receive messages asynchronously. Interacts with Java Message Service (JMS) • Multiple services can interact through messages • Web page • Servlet • JSF/JSP • Applet
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 23 JAVA EE COMPONENTS
Many components needs to be connected Introducing high coupling Contexts and Dependency Injection (CDI) • Contextual services in Java EE container • Integration of components with loose coupling and typesafety • Dependency injection
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 24 JAVA EE COMPONENTS - DEPENDENCY INJECTION
Example
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 25 JAVA EE PLATFORM
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 26 DEMO
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 27 SAMPLE CONFIGURATION
Get Eclipse Mars for Java EE + Install JBoss Tools Plugin* • http://tools.jboss.org/downloads/installation.html WildFly Application Server 9/10 PostgreSQL + pgAdmin Apache Maven Java 8 JDK Play examples here: https://java.net/projects/firstcup/ https://github.com/wildfly/quickstart https://java.net/downloads/glassfish-samples/javaee7-samples-1.0.zip
*http://tools.jboss.org/downloads/jbosstools/mars/4.3.0.Final.html#update_site
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 28 JBOSS SAMPLE APPS
1. Open Eclipse that has JBoss Tools installed * 2. File | New | Other 3. Examples | JBoss Tools | Project Examples | Next >> 4. Web Applications | helloworld | Next >> | select server/runtime 5. Download and Install.. | WildFly 9.0.1 | accept terms | fill path | Install 6. Wait until installs | Next | Use default location | Finish | wait | Finish*
7. Open readme.md and see “Run the Quickstart in JBoss Developer Studio or Eclipse”
*http://tools.jboss.org/downloads/jbosstools/mars/4.3.0.Final.html#update_site
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 29 Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 30 JBOSS SAMPLE APPS
8. Fix class dependencies is any [In my case pom.xml change]
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 31 Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 32 JBOSS SAMPLE APPS DEBUG
14. Servers | Right-click | Stop 15. Servers | Right-click | Debug 16. Put debug break point (double click) to • HelloService.java Line 28 • HelloWolrdServlet Line 55 17. Open web browser with address • http://localhost:8080/jboss-helloworld/HelloWorld 18. Switch back to eclipse and see Confirmation on Debug View | Yes
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 33 Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 34 JBOSS SAMPLE APPS DEBUG
19. Step next in debug view until line 58 then step into (out/in few time) 20. See the stack that corresponds to HelloService.createHelloMessage 21. See the parameter value : name = “World” 22. In the Debug panel click on HelloWorldServlet.doGet(…. 23. Change line 58 servlet param to Your Name! and repeat step 17 24. Click Resume (F8) in debug view 25. Nothing happen!? • Right-click server | publish • Restart server and try again • Still broken? • Right-click project | run as | run on server • Open server and pick the project | Full Publish | restart OR Remove
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 35 JBOSS SAMPLE APPS
• Components • HelloWorldServlet = @WebServlet("/HelloWorld") • Extends HttpServlet • Implementes doGet (HTTP GET) similarly doPost • Open in Eclipse HelloWorldServlet • hold ctrl and left click on HttpServlet • Maven fetches the source code for you! • CDI • Notice the connection HelloWorldServlet and HelloService • @Inject
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 36 HELLOWORLD-HTML5
Try: example helloworld-html5 • See index.html • HelloWorld no longer servlet instead a web service
@Path("/") public class HelloWorld { @Inject HelloService helloService;
@GET @Path("/json/{name}") @Produces("application/json") public String getHelloWorldJSON(@PathParam("name") String name) { return "{\"result\":\"" + helloService.createHelloMessage(name) + "\"}"; }
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 37 HELLOWORLD-HTML5
Try: example helloworld-html5 • See index.html • HelloWorld no longer servlet instead a web service
• Access http://localhost:8080/jboss-helloworld-html5/ • Then go to • http://localhost:8080/jboss-helloworld-html5/hello/json/aa • http://localhost:8080/jboss-helloworld-html5/hello/xml/aa
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 38 JAVA EE WEB PROJECT
Try: example JBoss Maven Archetypes / Java EE Web Project Finish deploy and go to http://localhost:8080/jboss-javaee6-webapp/index.jsf Add yourself to the form
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 39 Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 40 SEE THE STRUCTURE
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 41 SEE THE STRUCTURE Data Definition and Access • Member.java • See field annotations - validation • JPA + XML • EntityManager Producer– Resources.java • MemberRepository.java – finder! Presentation • index.html • JSF + Facelets • http://localhost:8080/jboss-javaee6-webapp/index.jsf REST • MemberResourceRESTService.java + JaxRsActivator.java • http://localhost:8080/jboss-javaee6-webapp/rest/members Business EJB • MemberRegistration.java @Stateless EJB • CDI inject entityManager = events Controllers • MemberListProducer.java – observer events • MemberController.java see #register() and binding to Member.java
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 42 WHERE TO GO NEXT?
See all sources at : https://github.com/jboss-developer/jboss-eap-quickstarts
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 43 HOMEWORK
1. Add person removal function 2. Add person info update feature 3. Make page transition to person detail though JSF dispatch 4. Connect to PostgreSQL database 5. Make a named query 1. https://github.com/javaee-samples/javaee7- samples/blob/master/jpa/storedprocedure/src/main/java/org/ja vaee7/jpa/storedprocedure/Movie.java 2. https://github.com/javaee-samples/javaee7- samples/blob/master/jpa/storedprocedure/src/main/java/org/ja vaee7/jpa/storedprocedure/MovieBean.java
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 44 INSTALL POSTGRES
Install portgres server Make postgres user a password Make a user testuser with somepass
$ sudo -u postgres psql postgres=> alter user postgres password ’XXX'; postgres=> create user testuser createdb createuser password 'somepass'; postgres=> create database testdb owner testuser ; postgres=> \q $ ...
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 45 INSTALL POSTGRES PGADMIN http://www.pgadmin.org/ Install and connect to localhost:5432 Use your user / password Or postgress / password
Add database testdb Owner testuser Definition|Template template0
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 46 SERVER ADMIN CONSOLE
Start server | Go to http://localhost:8080 and click administr. console It takes you to http://localhost:8080/console and redirects to http://localhost:9990/error/index.html
See the management instructions for console follow steps below - to add user
Go to your server bin folder such as cd ~/wildfly-9.0.1.Final/bin/
~/wildfly-9.0.1.Final/bin$ chmod +x ./add-user.sh ~/wildfly-9.0.1.Final/bin$ ./add-user.sh a [enter] admin [enter] admin [enter] *yes to all
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 47 REGISTER POSTGRES TO SERVER I.
1. Go again to http://localhost:8080/console and login admin admin
2. Read through https://developer.jboss.org/wiki/JBossAS7-DatasourceConfigurationForPostgresql 3. Download postgresql-9.3-1103.jdbc41.jar 4. And move it to ~/wildfly-9.0.1.Final/standalone/deployments 5. Restart server 6. Go to http://localhost:9990/console/App.html#profile/datasources 7. Click Add
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 48 REGISTER POSTGRES TO SERVER II.
7. Click Add | select PostgreSQL | Next | Next | Detected Driver
8. Pick Postgresql-9.3.. | Setup connection URL: jdbc:postgresql://localhost:5432/testdb Username: testuser Password: somepass 9. Click Test Connection if it passed then click Done
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 49 REGISTER POSTGRES TO SERVER III.
10. See the new data source and the driver name
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 50 CONNECT WEB APP TO POSTGRES VIA DRIVER
Go to jboss-javaee6-webapp-ds.xml and replace H2 with Postgres
Add dialect to persistence.xml
1. Open pgAdmin and right click databases node and refresh 2. The testdb appears 3. Open it | schemas | public 4. Open Tables | members 5. Right click | view data
Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 52 IF YOU STOP SERVER DATA DISAPPEAR
1. Go to persistence.xml 2. Replace properties with
2. Go to MemberRepository.java replace findAllOrderedByName public List Tomas Cerny, Software Engineering, FEE, CTU in Prague, 2016 54